Generally, a gaze tracking technology is a technology for detecting the movement of pupils, tracking the position of a gaze, detecting the movement of the pupils through an analysis of an image taken by a camera in real time, and tracking the gaze of a person by calculating the direction of the gaze based on fixed position reflected on the cornea.
Accordingly, in the related art, the gaze of a person located within a photographing range of a camera was tracked. However, in the case that a person deviates from the photographing range of the camera while the camera tracks the gaze in the event that a single camera is being used, a corresponding operation is generally stopped, and when an operation of tracking the gaze is performed using a plurality of cameras, the gaze of the person is tracked by detecting the person by the camera which does not detect the gaze of the person, again.
However, since such a gaze tracking technology should perform an operation of performing a calibration, the process of gaze tracking becomes complicated, and since a plurality of cameras are used, there is also a disadvantage that the cost of the product per unit would increase.